Add support to enable extend of in-use/attached volumes for libvirt/qemu driver

Registered by Trump.Zhang

We would like to add an extension to allow the option of extending in-use volumes for libvirt/qemu driver.

This requires a number of things to happen and some of which need Nova’s assist:

1. Cinder decides if the in-use/attached volume can be extended or not, which depends on the capability of the backend and the space usage limit set on the backend, such as used_ratio for NFS backend driver.
2. Cinder extends the volume. Some types of backend may need Nova’s assist to do the rescan to make the volume’s new size to be refreshed on compute node. These types of driver include non-file based volumes, such as volumes on IPSAN.
3. Make the update passed in to the guest instance. This depends on the hypervisor in use. Libvirt/Qemu driver has provided a “block_resize” interface to support this scenario, which will drain guest’s IO, extend the disk, and resume guest’s IO. This work need Nova’s assist.

There is a blueprint for the Cinder part of this at: https://blueprints.launchpad.net/cinder/+spec/inuse-extend-volume-extension

Blueprint information

Status:
Complete
Approver:
None
Priority:
Undefined
Drafter:
Trump.Zhang
Direction:
Needs approval
Assignee:
Trump.Zhang
Definition:
Obsolete
Series goal:
None
Implementation:
Unknown
Milestone target:
None
Completed by
Trump.Zhang

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